This national stage application claims priority from Japanese Patent Application No. JP 11-147521 filed on May 27, 1999.
The present invention relates to a disk apparatus, particularly a latch mechanism for preventing an actuator arm, which is a component of the disk apparatus, from flying out from an unloading position because of an external shock. More particularly, the invention relates to an inertial latch that utilizes an inertial operation.
FIG. 13 is a diagram showing the essential parts of the inertial latch of a conventional disk apparatus 120.
In the same diagram, the central portion of a disk 101 is held integrally on a hub 118 of a spindle motor 117 disposed on a base 100 and is rotated at a desired speed. An actuator arm 102 is freely rotatably held on a rotating shaft 105 stood up in the base 100 and is driven in the directions of arrows L1 and M1 by means of a voice coil motor (not shown). The voice coil motor will hereinafter be referred to as a VCM.
The actuator arm 102 has a slider 103 formed on the point end portion thereof through suspension means (not shown). At predetermined positions on this slider 103, read and write heads are disposed. If the actuator arm 102 is loaded and rotated in the direction of arrow L1 over the recording surface of the disk 101 being rotated, the slider 103 flies over the recording surface of the disk 101 and the read and write heads are opposed with a predetermined space to the recording surface.
When the actuator arm 102 is unloaded to its home position, a tab 119 of the point end portion of the actuator arm 102 is placed on a ramp 104 and the actuator arm 102 is locked in that position by slight regulating force such as frictional force.
The actuator arm 102 holds the slider 103, and at the opposite positions from this slider 103 with respect to the rotating shaft 105, coil supports 106a and 106b are formed so that the coil of the VCM (not shown) is interposed therebetween.
When the actuator arm 102 is at the position shown in FIG. 13, the coil support 106a abuts an outer crash stop (hereinafter referred to as an outer C/S) 107 having elasticity and therefore the rotation of the actuator arm 102 in the direction of arrow M1 is regulated. This position is referred to as a home position for the actuator arm 102.
A lever 109 curved at an obtuse angle is freely rotatably held on a rotating shaft 108 stood up in the base 100, and in the point end portion of the lever 109, a pair of operating pins 110 and 111 is formed with a predetermined space. A latch 116 is freely rotatably held on a rotating shaft 112 stood up in the base 100, and has a first abutting portion 113 that the operating pin 111 of the lever 109 abuts and a second abutting portion 114 that the operating pin 110 abuts.
The point end portion of the latch 116 on the same side as the second abutting portion 114 with respect to the rotating shaft 112 has a hooked protrusion 115. The hooked protrusion 115 engages with the coil support 106a of the actuator arm 102 at predetermined timing to be described later, thereby regulating rotation of the actuator arm 102 in the direction of arrow L1.
The latch 116 is slightly urged clockwise by an urging means (not shown) so that it does not interfere with rotation of the actuator arm 102 when access to the disk is allowed. With the urging force, the latch 116 and the lever 109 are balanced at an actuator-release position shown in FIG. 13 where both the operating pin 111 and the first abutting portion 113 and also both the operating pin 110 and the second abutting portion 114 abut each other at the same time.
The actuator arm 102 holding the coil, the lever 109, and the latch 116 are each constructed so that the center of gravity is present on each axis of rotation and rotational force does not occur due to a shock that is produced by linear movement.
On the other hand, because of a shock produced by movement accompanied by rotation, there is a possibility that the actuator arm 102 will rotate and fly out from its unloading position. But, the inertial latch has the function of preventing the actuator arm 102 from flying out from the unloading position.
There are various kinds of motions accompanied by rotation and it is not easy to analyze all the motions. But, as a simple example, consider the case where the hard-disk apparatus is rotated on a point on the apparatus and crashed against a fixed surface.
FIG. 16 shows a test table 130 for giving a shock to the hard-disk apparatus 120. This test table 130 is used for freely rotatably holding the entire hard-disk apparatus 120 and constructed so that the axis of the rotating shaft 131 approximately aligns with that of the rotating shaft 105 of the actuator arm 102.
FIG. 16 shows the condition when the disk 101 is located above the rotating shaft 131. If the hard-disk apparatus 120 is rotated from this condition in the direction of arrow L4 to crash the side portion 121 thereof against a rubber stopper 132 on a stopper table 133, as shown in FIG. 17, this shock causes the actuator arm 102, the lever 109, and the latch 116 to rotate counterclockwise, i.e., in the directions of arrows L1, L2, and L3, respectively, as shown in FIG. 14. In the same figure, the movement of the inertial latch at this time is shown. The operating pin 111 of the lever 109 pushes the first abutting portion 113 of the latch 116 and assists the latch 116 to rotate in the direction of arrow L3. The rotation of the latch 116 in the direction of arrow L3 causes the protrusion 115 to engage with the coil support 106a of the actuator arm 102, whereby the rotation of the actuator arm 102 in the direction of arrow L1 is prevented.
Note that it is considered that nearly the same angular acceleration is produced in the actuator arm 102, the latch 116, and the lever 109, respectively. With respect to the angle through which the actuator arm 102 moves from its home position to the position regulated by the latch 116, the angle through which the lever 109 moves from the actuator-arm-release position to the regulating position in order to rotate the latch 116 is designed to be smaller. For this reason, the latch 116 rotates rapidly, whereby the engagement between the protrusion 115 of the latch 116 and the coil support 106a of the actuator arm 102 becomes possible.
Next, if the hard-disk apparatus 120 is rotated from the condition in FIG. 16 in the direction of arrow M4 to crash the side portion 122 thereof against the rubber stopper 132 on the stopper table 133, as shown in FIG. 18, this shock causes the actuator arm 102, the lever 109, and the latch 116 to rotate clockwise, i.e., in the directions of arrows M1, M2, and M3, respectively, as shown in FIG. 15. In the same figure, the movement of the inertial latch at this time is shown.
Although the latch 116 attempts to rotate in the direction of arrow M3, finally it rotates in the direction of arrow L3, because the force of pushing the second abutting portion 114 of the latch 116 by the operating pin 110 of the lever 109 having a larger moment of inertia is strong.
On the other hand, the actuator arm 102 is rotated once in the direction of arrow M1, but the coil support 106a crashes against the outer C/S 107, which has elasticity and limits rotation in the same direction. With the reaction, the actuator arm 102 rotates in the direction of arrow L1.
However, at this time, the latch 116 rotates in the direction of arrow L3 as previously described and the protrusion 115 engages with the coil support 116a. In a condition such as the one shown in FIG. 15, the rotation of the actuator arm 102 in the direction of arrow L1 is prevented.
In the aforementioned manner, the actuator arm 102 in its home position is prevented from rotating in the direction of arrow L1 because of an external shock, whereby the slider 103 can be prevented from contacting the recording surface of the disk 101 not being rotated.
In an inertial latch such as that mentioned above, when the side portion 121 of the hard-disk apparatus 120 crashes against the rubber stopper 132 on the stopper table 133 as shown in FIG. 17, for example, movement of each part will differ if the shock exceeds a certain level.
FIG. 19 is a timing diagram showing movement of each part at the time of the shock. The horizontal axis indicates the lapse of time t, and the vertical axis of FIG. 19(a) indicates the strength of the shock. The vertical axis of FIG. 19(b) indicates the rotational amount of the actuator arm 102 in the directions of arrows L1 and M1, the vertical axis of FIG. 19(c) the rotational amount of the latch 116 in the directions of arrows L3 and M3, and the vertical axis of FIG. 19(d) the rotational amount of the lever 109 in the directions of arrows L2 and M2.
In FIG. 19(b) the rotational range Q indicated by two broken lines indicates a rotational range of the actuator arm 102 engageable with the latch 116. In FIG. 19(c), the rotational range R indicated by two broken lines indicates a rotational range of the latch 116 engageable with the actuator arm 102, and the upper broken line S also represents the maximum rotational position of the latch 116.
If a shock occurs at time t1, the actuator arm 102, the lever 109, and the latch 116 all rotate in the counterclockwise directions of arrows L1, L2, and L3, respectively, as previously described. The respective rotations stop around time t2. This is why the protrusion 115 of the latch 116 engages with the coil support 106a of the actuator arm 102. If the first shock is strong, the actuator arm 102 is rotated in the direction of arrow M1 by the reaction of the aforementioned engagement (i.e., crash).
And at time t3, the actuator arm 102 crashes against the outer C/S at the home position. With the reaction, the actuator arm 102 is rotated again in the direction of arrow L1. At this time, the latch 116 has returned to the actuator-release position by the aforementioned urging force, so the actuator arm 102 continues to rotate in the same direction.
If the actuator arm 102 at the home position in this manner is subjected to a shock exceeding a certain level, the rotation in the direction of arrow L1 will no longer be regulated and the slider 103 will contact the recording surface of the disk 101 not being rotated.
If such a situation occurs, scratches will occur on the recording surface of the disk 101 and there will be cases where, because of the contact friction, the spindle motor 117 will no longer be able to rotate.
Besides an external shock, if during operation the actuator arm 102 runs recklessly and crashes into the outer C/S 107, the reaction will cause the actuator arm 102 to rotate in the direction of arrow L1 and there will be a possibility that the actuator arm 102 will fly out over the recording surface of the disk 101. At this time, if the spindle motor 117 stops, the slider 103 will contact the recording surface of the disk 101 and similar inconvenience will occur.
One object of the present invention is to provide a disk apparatus which is capable of reliably preventing rotation of its actuator arm that could not be prevented by the conventional mechanism, when a great shock occurs or when the actuator arm 102 runs recklessly.
In one embodiment of the present invention there is provided a disk apparatus comprising: an actuator arm with an end rotatable in a first direction from its home position located outside a recording surface of a disk so that the end can be moved over the recording surface. The apparatus also has a latch that is rotatable between a restricted position and a release position. The latch engages the actuator arm at the restricted position to regulate the rotation of the actuator arm in the first direction. In addition, the apparatus has a lever greater in moment of inertia than the latch. The lever engages the latch and rotates to make the latch rotate to the restricted position. Finally, a stopper is used to regulate rotations of the actuator arm from the home position in a second direction opposite from the first direction. Furthermore, at least a portion of at least either the actuator arm or the stopper is elastically deformable so that the actuator arm engages elastically with the stopper. The latch is also provided with an engaging member that engages with the actuator arm to make the latch rotate to the restricted position by a shock produced by the engagement, when the actuator arm is further rotated by the elastic deformation of the elastically deformable member due to the engagement of the actuator arm and the stopper.